Springer Online Journal Archives 1860-2000
Summary Soybean seedlings (Glycine max) were incubated in narrow temperature regimes to study the effects of heat shock on cell structures. The incubation temperatures used were as follows: 1. 28 °C (2h); 2. 40 °C (2h); 3. 45 °C (2h); 4. 40 °C (2h)→45 °C (2h); 5. 47. 5 °C (10 min); 6. 40 °C (2h)→47. 5 °C (10 min). Both optical and electron micrographs were taken of the different tissues of root meristems as they responded to heat shock. Cells of roots heated to 45 °C (2h) or 47.5 °C (10 min) with lethal treatment showed drastic heat injuries:e.g., membrane damage, coagulated plasmolysis, protoplasmic contraction, and leakage of cell content. Nucleolar segregation occurred in cells treated at both lethal and supraoptimal temperatures. Seedlings preincubated at 40 °C (2 h) became thermo-tolerant to lethal temperature treatment of 45 °C (2 h) or 47.5 °C (10 min), by protecting the plasmalemma, mitochondria, plastids and nuclei from heat damage. Without preincubation, however, these structures were destroyed.
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